Baseline Strategy Research Articles

Interpersonal strategies for disturbance attenuation during a rhythmic joint motor action

Helping someone carry a table is fairly easy; however, our understanding of such joint motor actions is still poorly understood. We studied how pairs of human subjects (referred to as dyads) collaborate physically to attenuate external mechanical perturbations during a target tracking task. Subjects tracked a target moving in a slow and predictable way using wrist flexion/extension movements, with and without destabilizing torque perturbations. Dyad strategies were classified using interaction torques and muscular activity. During unperturbed interactions (baseline), the dyads tended to stabilize on a particular strategy. The baseline strategy was not the same in all dyads, suggesting that the solution to the task was not global but specific to each particular dyad. After several trials of unperturbed interactions, we introduced mechanical vibrations and analyzed the adaptation process. Dyads showed a tendency to counteract the external disturbances by first increasing co-contraction within each subject (independent co-contraction), and then raising the amount of opposing interaction torques (dyadic co-contraction) with increased perturbation amplitude. The introduction of perturbations impelled dyads to abandon their unperturbed baseline strategy and adopt a more common strategy across dyads, suggesting attractor solutions. Our results establish a framework for future human–human interaction studies, and have implications in human motor control as well as human–robot and robot–robot interactions.

Robust Emission Management Strategy to Meet Real-World Emission Requirements for HD Diesel Engines

Heavy-duty diesel engines are used in different application areas, like long-haul, city distribution, dump truck and building and construction industry. For these wide variety of areas, the engine performance needs to comply with the real-world legislation limits and should simultaneously have a low fuel consumption and good drivability. Meeting these requirements takes substantial development and calibration effort, where an optimal fuel consumption for each application is not always met in practice. TNO's Integrated Emission Management (IEM) strategy, is able to deal with these variations in operating conditions, while meeting legislation limits and obtaining on-line cost optimization. Based on the actual state of the engine and aftertreatment, optimal air-path setpoints are computed, which balances EGR and SCR usage. Due to IEM's adaptation characteristics based on the actual state of engine and aftertreatment system, the strategy is robust for varying conditions during real-world operation. This is especially of interest, since real-world emissions become increasingly important: in-use compliance, including Not-To-Exceed (NTE) areas, challenging On-Board-Diagnostics requirements and In-Use Performance Ratio (IUPR) monitoring. The main contribution of this work is to demonstrate the robustness of IEM on a variety of real-world cycles by means of a simulation study. Whereas previous publications focus on demonstration of the IEM strategy on Type Approval cycles, this work can be seen as an extension, which also addresses In-Service Conformity (ISC). This paper discusses in detail the performance and robustness of the IEM strategy at these cycles compared with a state-of-the-art Euro-VI engine control strategy (baseline). Consequent improvements are obtained among the different cycles. Fuel consumption and fluid cost are reduced up to 2% and 1.7%, respectively, compared to this baseline strategy.

GhostRider

This paper presents a new, co-designed compiler and architecture called GhostRider for supporting privacy preserving computation in the cloud. GhostRider ensures all programs satisfy a property called memory-trace obliviousness (MTO): Even an adversary that observes memory, bus traffic, and access times while the program executes can learn nothing about the program's sensitive inputs and outputs. One way to achieve MTO is to employ Oblivious RAM (ORAM), allocating all code and data in a single ORAM bank, and to also disable caches or fix the rate of memory traffic. This baseline approach can be inefficient, and so GhostRider's compiler uses a program analysis to do better, allocating data to non-oblivious, encrypted RAM (ERAM) and employing a scratchpad when doing so will not compromise MTO. The compiler can also allocate to multiple ORAM banks, which sometimes significantly reduces access times.We have formalized our approach and proved it enjoys MTO. Our FPGA-based hardware prototype and simulation results show that GhostRider significantly outperforms the baseline strategy.

GhostRider

This paper presents a new, co-designed compiler and architecture called GhostRider for supporting privacy preserving computation in the cloud. GhostRider ensures all programs satisfy a property called memory-trace obliviousness (MTO): Even an adversary that observes memory, bus traffic, and access times while the program executes can learn nothing about the program's sensitive inputs and outputs. One way to achieve MTO is to employ Oblivious RAM (ORAM), allocating all code and data in a single ORAM bank, and to also disable caches or fix the rate of memory traffic. This baseline approach can be inefficient, and so GhostRider's compiler uses a program analysis to do better, allocating data to non-oblivious, encrypted RAM (ERAM) and employing a scratchpad when doing so will not compromise MTO. The compiler can also allocate to multiple ORAM banks, which sometimes significantly reduces access times.We have formalized our approach and proved it enjoys MTO. Our FPGA-based hardware prototype and simulation results show that GhostRider significantly outperforms the baseline strategy.

Mode-switching-based active control of a powertrain system with non-linear backlash and flexibility for an electric vehicle during regenerative deceleration

Regenerative braking provided by an electric powertrain is very different from conventional friction braking with respect to the system dynamics. During regenerative decelerations, the powertrain backlash and flexibility excite driveline oscillations, causing the vehicle driveability and the blended brake performance to deteriorate. In this article, system models, including a powertrain model with non-linear backlash and flexibility, and a hydraulic brake system model, are developed. The effects of the powertrain backlash and the flexibility on the vehicle driveability during regenerative deceleration are analysed. To improve the driveability and the blended braking performance of an electric vehicle further, a mode-switching-based active control algorithm with a hierarchical architecture is developed providing compensation for the backlash and the flexibility. The proposed control algorithms are simulated and compared with the baseline strategy under the regeneration braking process. The simulation results show that the vehicle driveability and the blended braking performance can be significantly enhanced by the developed active control algorithm.

An adaptive failure detector based on quality of service in peer-to-peer networks.

The failure detector is one of the fundamental components that maintain high availability of Peer-to-Peer (P2P) networks. Under different network conditions, the adaptive failure detector based on quality of service (QoS) can achieve the detection time and accuracy required by upper applications with lower detection overhead. In P2P systems, complexity of network and high churn lead to high message loss rate. To reduce the impact on detection accuracy, baseline detection strategy based on retransmission mechanism has been employed widely in many P2P applications; however, Chen's classic adaptive model cannot describe this kind of detection strategy. In order to provide an efficient service of failure detection in P2P systems, this paper establishes a novel QoS evaluation model for the baseline detection strategy. The relationship between the detection period and the QoS is discussed and on this basis, an adaptive failure detector (B-AFD) is proposed, which can meet the quantitative QoS metrics under changing network environment. Meanwhile, it is observed from the experimental analysis that B-AFD achieves better detection accuracy and time with lower detection overhead compared to the traditional baseline strategy and the adaptive detectors based on Chen's model. Moreover, B-AFD has better adaptability to P2P network.

An integrated national open apprenticeship scheme as a baseline strategy for technological development

The main thesis of this paper is that the National Open Apprenticeship Scheme of the Nigerian National Directorate of Employment should be integrated into the mainstream of the national educational and socio–technical development program as a baseline strategy for national technological development. By considering particular vocational occupational areas, the paper presents a structural and operational model of the proposed integrated scheme.

Integrated Energy and Emission Management for Diesel Engines with Waste Heat Recovery Using Dynamic Models

Rankine-cycleWasteHeatRecovery (WHR)systems are promising solutions to reduce fuel consumption for trucks. Due to coupling between engine andWHR system, control of these complex systems is challenging. This study presents an integrated energy and emission management strategy for an Euro-VI Diesel engine withWHRsystem. This Integrated Powertrain Control (IPC) strategy optimizes the CO2-NOx trade-off by minimizing online the operational costs associated with fuel and AdBlue consumption. Contrary to other control studies, the proposed control strategy optimizes overall engine-aftertreatment-WHR systemperformance and dealswith emission constraints. Fromsimulations, the potential of this IPC strategy is demonstrated over a World Harmonized Transient Cycle (WHTC) using a highfidelity simulationmodel. These results are compared with a state-of-the-art baseline engine control strategy. By applying the IPC strategy, an additional 2.6%CO2 reduction is achieved compare to the baseline strategy, while meeting the tailpipeNOx emission limit. In addition, the proposed low-levelWHR controller is shown to deal with the cold start challenges.

Cost-effectiveness analysis of intra-articular injections of a high molecular weight bioengineered hyaluronic acid for the treatment of osteoarthritis knee pain

Objective:To determine the cost-effectiveness of bioengineered hyaluronic acid (BioHA, 1% sodium hyaluronate) intra-articular injections in treating osteoarthritis knee pain in poor responders to conventional care (CC) including non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics.Methods:Two decision analytic models compared BioHA treatment with either continuation of patient’s baseline CC with no assumption of disease progression (Model 1), or CC including escalating care costs due to disease progression (NSAIDs and analgesics, corticosteroid injections, and surgery; Model 2). Analyses were based on patients who received two courses of 3-weekly intra-articular BioHA (26-week FLEXX Trial + 26-week Extension Study). BioHA group costs included fees for physician assessment and injection regimen, plus half of CC costs. Cost-effectiveness ratios were expressed as averages and incremental costs per QALY. One-way sensitivity analyses used the 95% confidence interval (CI) of QALYs gained in BioHA-treated patients, and ±20% of BioHA treatment and CC costs. Probabilistic sensitivity analyses were performed for Model 2.Results:For 214 BioHA patients, the average utility gain was 0.163 QALYs (95% CI = −0.162 to 0.488) over 52 weeks. Model 1 treatment costs were $3469 and $4562 for the BioHA and CC groups, respectively; sensitivity analyses showed BioHA to be the dominant treatment strategy, except when at the lower end of the 95% CI. Model 2 annual treatment costs per QALY gained were $1446 and $516 for the BioHA and CC groups, respectively. Using CC as baseline strategy, the incremental cost-effectiveness ratio (ICER) of BioHA was $38,741/QALY gained, and was sensitive to response rates in either the BioHA or CC groups.Conclusion:BioHA is less costly and more effective than CC with NSAIDs and analgesics, and is the dominant treatment strategy. Compared with escalating CC, the $38,741/QALY ICER of BioHA remains within the $50,000 per QALY willingness-to-pay threshold to adopt a new technology.

On False Data-Injection Attacks against Power System State Estimation: Modeling and Countermeasures

It is critical for a power system to estimate its operation state based on meter measurements in the field and the configuration of power grid networks. Recent studies show that the adversary can bypass the existing bad data detection schemes, posing dangerous threats to the operation of power grid systems. Nevertheless, two critical issues remain open: 1) how can an adversary choose the meters to compromise to cause the most significant deviation of the system state estimation, and 2) how can a system operator defend against such attacks? To address these issues, we first study the problem of finding the optimal attack strategy--i.e., a data-injection attacking strategy that selects a set of meters to manipulate so as to cause the maximum damage. We formalize the problem and develop efficient algorithms to identify the optimal meter set. We implement and test our attack strategy on various IEEE standard bus systems, and demonstrate its superiority over a baseline strategy of random selections. To defend against false data-injection attacks, we propose a protection-based defense and a detection-based defense, respectively. For the protection-based defense, we identify and protect critical sensors and make the system more resilient to attacks. For the detection-based defense, we develop the spatial-based and temporal-based detection schemes to accurately identify data-injection attacks.

Task mapping stencil computations for non-contiguous allocations

We examine task mapping algorithms for systems that allocate jobs non-contiguously. Several studies have shown that task placement affects job running time. We focus on jobs with a stencil communication pattern and use experiments on a Cray XE to evaluate novel task mapping algorithms as well as some adapted to this setting. This is done with the miniGhost miniApp which mimics the performance of CTH, a shock physics application. Our strategies improve average and single-run times by as much as 28% and 36% over a baseline strategy, respectively.

Limiting disproportionate disaccommodation in design for human variability

In the design of artefacts, tasks and environments for human use, the body dimensions of the target population are a critical element in spatial optimisation of the design. This study examines how the choices designers make affect the ability of different user groups to safely and effectively interact with a designed artefact. Due to the variability in body size and shape across different demographic groups, heterogeneous user populations are unlikely to experience uniform levels of performance. The associated variability in the rate of unacceptable user conditions is referred to here as disproportionate disaccommodation. This is both an ethical and a performance concern that can partially be addressed through improved design practice. Three methods for incorporating the consideration of user demographics and the corresponding variability in body size and shape are presented. They are compared with a baseline strategy in terms of accommodation and cost.

Determinants of Amputation-Free Survival After Peripheral Vascular Intervention for Critical Limb Ischemia

Methods: We performed a cost-effectiveness analysis comparing SE and ilio-femoral PS with a baseline strategy of nonsupervised exercise (NSE). Estimates for costs and outcomes were obtained from the medical literature (Table) and the Bureau of Labor Statistics. Costs were adjusted to 2012 US Dollars. Effectiveness was measured as the maximum walking distance (MWD) in meters by treadmill testing performed at 1-year. The primary endpoint was cost-effectiveness measured in dollars per meter walked. Because of a 1-year time horizon, discounting was not used. Results: The average cost-effectiveness of NSE/SE/PS in dollars per meter walked was 15.4/19.8/51.6, respectively. When compared with NSE, the incremental cost-effectiveness ratio for SE was $24.96/m. For PS, it was $81.1/m. One-way sensitivity analyses (Table, Column 3) demonstrated that SE was a robust strategy in that it was more cost-effective than PS in all scenarios. PS was both more costly and less effective (ie, dominated) if MWDPS 424 m. Conclusion: When compared with NSE, SE is a more cost-effective strategy than PS for the treatment of iliofemoral disease in IC.

Financial implications of male circumcision scale-up for the prevention of HIV and other sexually transmitted infections in a sub-Saharan African community.

The financial implications of male circumcision (MC) scale-up in sub-Saharan Africa associated with reduced HIV have been evaluated. However, no analysis has incorporated the expected reduction of a comprehensive set of other sexually transmitted infections including human papillomavirus, herpes simplex virus type 2, genital ulcer disease, bacterial vaginosis, and trichomoniasis. A Markov model tracked a dynamic population undergoing potential MC scale-up, as individuals experienced MC procedures, procedure-related adverse events, and MC-reduced sexually transmitted infections and accrued any associated costs. Rakai, Uganda, was used as a prototypical rural sub-Saharan African community. Monte Carlo microsimulations evaluated outcomes under 4 alternative scale-up strategies to reach 80% MC coverage among men aged 15 to 49 years, in addition to a baseline strategy defined by current MC rates in central Uganda. Financial outcomes included direct medical expenses only and were evaluated over 5 and 25 years. Costs were discounted to the beginning of each period, coinciding with the start of MC scale-up, and expressed in US $2012. Cost savings from infections averted by MC vary from US $197,531 after 5 years of a scale-up program focusing on adolescent/adult procedures to more than US $13 million after 25 years, under a strategy incorporating increased infant MCs. Over a 5-year period, reduction in HIV contributes to 50% of cost savings, and for 25 years, this contribution rises to nearly 90%. Sexually transmitted infections other than HIV contribute to cost savings associated with MC scale-up. Previous analyses, focusing exclusively on the financial impact through averted HIV, may have underestimated true cost savings by 10% to 50%.

Frequency and Intensity of Postoperative Surveillance After Curative Treatment of Pancreatic Cancer: A Cost-Effectiveness Analysis

Few data exist to guide oncologic surveillance following curative treatment of pancreatic cancer. We sought to identify a rational, cost-effective postoperative surveillance strategy. We constructed a Markov model to compare the cost-effectiveness of 5 postoperative surveillance strategies. No scheduled surveillance served as the baseline strategy. Clinical evaluation and carbohydrate antigen (CA) 19-9 testing without/with routine computed tomography and chest X-ray at either 6- or 3-month intervals served as the 4 comparison strategies of increasing intensity. We populated the model with symptom, recurrence, treatment, and survival data from patients who had received intensive surveillance after multimodality treatment at our institution between 1998 and 2008. Costs were based on Medicare payments (2011 US dollars). The baseline strategy of no scheduled surveillance was associated with a postoperative overall survival (OS) of 24.6 months and a cost of $3837/patient. Clinical evaluation and CA 19-9 assay every 6 months until recurrence was associated with a 32.8-month OS and a cost of $7496/patient, with an incremental cost-effectiveness ratio (ICER) of $5364/life-year (LY). Additional routine imaging every 6 months incrementally increased total cost by $3465 without increasing OS. ICERs associated with clinic visits every 3 months without/with routine imaging were $127,680 and $294,696/LY, respectively. Sensitivity analyses changed the strategies' absolute costs but not the relative ranks of their ICERs. Increasing the frequency and intensity of postoperative surveillance of patients after curative therapy for pancreatic cancer beyond clinical evaluation and CA 19-9 testing every 6 months increases cost but confers no clinically significant survival benefit.

Diagnostic Evaluation in Patients with Intractable Epilepsy and Normal Findings on MRI: A Decision Analysis and Cost-Effectiveness Study

Patients with focal intractable epilepsy and normal MR imaging findings frequently undergo further diagnostic tests to localize the epileptogenic zone. The aim of this study was to determine the cost-effective diagnostic strategy that will identify the epileptogenic zone in patients with suspected focal intractable epilepsy and normal MR imaging findings by using decision analysis. A Markov decision model was constructed by using sensitivities and specificities of test strategies, seizure outcomes following surgical and medical treatment, cost, utilities, probabilities, and standardized mortality ratios. We compared 6 diagnostic test strategies: PET, ictal SPECT, and MEG individually; and combinations of PET+SPECT, PET+MEG, and SPECT+MEG. The outcomes measured were health care costs, QALY, and ICER. One-way and probabilistic sensitivity analyses were conducted to adjust for uncertainties in model parameters. The preferred strategies were PET+MEG and SPECT. The health care cost of the baseline strategy (PET+MEG) was $95,612 with 16.30 QALY gained. SPECT cost $97,479 with 16.45 QALY gained and an ICER of $12,934/QALY gained compared with those in PET+MEG. One-way sensitivity analyses showed that the decisions of the model were sensitive to variations in sensitivity and specificity of the test strategies. Probabilistic sensitivity analysis showed that when the willingness to pay was <$10,000, PET+MEG was the favored strategy, but the favored strategy changed to SPECT when the willingness to pay was >$10,000. PET+MEG and SPECT were the preferred strategies in the base case. The choice of test was dependent on the sensitivity and specificity of test strategies and willingness to pay. Further study with a larger sample size is needed to obtain better estimates of sensitivity and specificity of diagnostic tests.

Aligning strategy to threat: a baseline anti‐terrorism strategy for hotels

PurposeAlthough the threat of terrorist attacks is not a new phenomenon for hotels, limited literature exists on measures that hotels can take to prevent them or limit their damage. The purpose of this paper is to propose a baseline strategy to address this threat.Design/methodology/approachUsing the terrorist attack cycle and the security function models introduced in this paper, 19 hotel security experts, members of an international working group on terrorism, were tasked to reach consensus on a baseline anti‐terrorist strategy for a hotel. To reach this consensus, the study employed the Nominal Group Technique.FindingsThe study presents a six‐step baseline anti‐terrorism strategy and a series of measures and actions under each step. In the centre of this strategy lies the disruption of the terrorist attack cycle.Research limitations/implicationsThere are limitations inherent to the Nominal Group Technique which may not allow the generalizability of the findings. However, every effort was made to ensure the reliability and validity of the study.Practical implicationsThe study suggests a shift from physical protection alone to a more intelligence‐led approach. Counter‐surveillance, terrorist behavioral analysis, higher visibility of security measures, stronger relationships with local community leaders, collaborative relationships with emergency response agencies and strategic use of risk intelligence providers will have to take a higher place in the agendas of hotel security departments.Originality/valueThe paper presents, for the first time, two models that industry practitioners will find useful when designing security policies: the terrorist attack cycle and the security function model. Each component of the proposed strategy provides a starting point for the design of security strategies tailored on the security needs and budget of any hotel property.

In-vessel dust and tritium control strategy in ITER

Abstract A baseline strategy for dust and tritium-inventory control and recovery in ITER has been established and preparations are underway for its implementation. Limits on dust and tritium-inventory are an integral part of the ITER safety case and are fixed at 1 kg for tritium, 1000 kg for mobilisable dust and 11 kg (beryllium)/76 kg (tungsten) for dust on hot surfaces. Maximum average T-retention rates of ∼1 g/shot are estimated for baseline inductive operation at QDT = 10, suggesting that the in-vessel T-retention could reach the administrative limit of 640 g in as little as ∼2 months of operation. Baking is expected to remove a significant fraction of the T co-deposited on the divertor targets. Despite large uncertainties, dust quantities are expected to remain well below safety limits over the divertor cassette lifetime. In situ aspiration during divertor cassette exchange is foreseen as the main dust removal technique.

Redundancy in electronic health record corpora: analysis, impact on text mining performance and mitigation strategies

BackgroundThe increasing availability of Electronic Health Record (EHR) data and specifically free-text patient notes presents opportunities for phenotype extraction. Text-mining methods in particular can help disease modeling by mapping named-entities mentions to terminologies and clustering semantically related terms. EHR corpora, however, exhibit specific statistical and linguistic characteristics when compared with corpora in the biomedical literature domain. We focus on copy-and-paste redundancy: clinicians typically copy and paste information from previous notes when documenting a current patient encounter. Thus, within a longitudinal patient record, one expects to observe heavy redundancy. In this paper, we ask three research questions: (i) How can redundancy be quantified in large-scale text corpora? (ii) Conventional wisdom is that larger corpora yield better results in text mining. But how does the observed EHR redundancy affect text mining? Does such redundancy introduce a bias that distorts learned models? Or does the redundancy introduce benefits by highlighting stable and important subsets of the corpus? (iii) How can one mitigate the impact of redundancy on text mining?ResultsWe analyze a large-scale EHR corpus and quantify redundancy both in terms of word and semantic concept repetition. We observe redundancy levels of about 30% and non-standard distribution of both words and concepts. We measure the impact of redundancy on two standard text-mining applications: collocation identification and topic modeling. We compare the results of these methods on synthetic data with controlled levels of redundancy and observe significant performance variation. Finally, we compare two mitigation strategies to avoid redundancy-induced bias: (i) a baseline strategy, keeping only the last note for each patient in the corpus; (ii) removing redundant notes with an efficient fingerprinting-based algorithm. aFor text mining, preprocessing the EHR corpus with fingerprinting yields significantly better results.ConclusionsBefore applying text-mining techniques, one must pay careful attention to the structure of the analyzed corpora. While the importance of data cleaning has been known for low-level text characteristics (e.g., encoding and spelling), high-level and difficult-to-quantify corpus characteristics, such as naturally occurring redundancy, can also hurt text mining. Fingerprinting enables text-mining techniques to leverage available data in the EHR corpus, while avoiding the bias introduced by redundancy.

Integrated Emission Management for Cost Optimal EGR-SCR Balancing in Diesels

The potential of a cost-based optimization method is experimentally demonstrated on a Euro-VI heavy-duty diesel engine. Based on the actual engine-aftertreatment state, this model-based Integrated Emission Management (IEM) strategy minimizes operational (fuel and AdBlue) costs within emission constraints by real-time computation of optimal air management set points. This work discusses the control design in detail. By EGR-SCR balancing, fuel consumption and operational costs are reduced by 2.1% and 1.5%, respectively, compared to the baseline strategy over the hot World Harmonized Transient Cycle. Due to its adaptation characteristics, the IEM strategy is robust for varying conditions during real-world operation.